1. Field of the Invention
The present invention relates to a simulation apparatus and method for simulating an electric current flowing in an electronic apparatus and an intensity of an electromagnetic field radiated from the electronic apparatus by using the moment method and to a memory medium storing a program for realizing the simulation apparatus therein, more particularly relates to a simulation apparatus and method using the moment method for making simulation in the time domain possible and a memory medium storing a program for realizing the simulation apparatus therein.
One of the rules imposed by society on electronic apparatuses is that they should not emit more than a predetermined level of undesired radio waves or noise. This is now being strictly regulated by the standards of many countries.
A variety of technologies, such as shielding technologies and filtering technolgies, are used in order to satisfy such radio wave regulations, but use of these requires the development of simulation technology for making it possible to quantitatively simulate to which degree they can reduce the radio waves.
Another rule imposed on electronic apparatuses by society is that they should not be influenced by less than a predetermined level of radio waves or noise radiated from other electronic apparatuses. This too is now being strictly regulated by the standards of many countries.
2. Description of the Related Art
In order to satisfy such radio wave regulations, development of simulation technology for making it possible to clarify why an electronic apparatus radiates undesired radio waves or noise or why an electronic apparatus malfunctions due to the radio waves or noise is necessary.
Development of the latter simulation technology requires a simulation apparatus which can simulating the electric current changing over time which will flow in an electronic apparatus due to noise or the like and the intensity of the electromagnetic field changing over time which is radiated from the electronic apparatus. Nevertheless, no such simulation apparatus for simulating such an electric current and the intensity of an electromagnetic field changing over time has yet been commercialized. The reason for this will be explained in detail later with reference to the drawings.
An object of the present invention is to provide a novel simulation apparatus and method using a moment method which uses approximation expressions explained in detail later to make it possible to simulate a temporally changing electric current changing over time which flows in an electronic apparatus due to noise or the like and an intensity of an electromagnetic field changing over time which is radiated from an electronic apparatus and to provide a memory medium storing a program for realizing the simulation apparatus therein.
To attain the above object, the present invention is of a configuration which simulates an electric current by solving simultaneous equations of the moment method defining a relationship among the mutual impedance between elements of the electronic apparatus, a wave source, and the electric current flowing through the elements and, here, is provided with a means for calculating the mutual impedance at a sampling frequency and calculating approximation coefficients for when expressing the mutual impedance by a defined approximation expression from the calculated value and the sampling frequency; a means for forming simultaneous differential equations by setting the calculated approximation coefficients and an initial value for the simultaneous differential equations derived by performing a Fourier transform on the simultaneous equations of the moment method into which the approximation expression has been substituted; and a means for calculating the electric current of the time domain flowing in a specified element by solving the formed simultaneous differential equations.